Also, dog owners frequently describe how smart their cold-nosed friends are, how they know the words for large numbers of toys and other objects, and how they understand and sometimes obey numerous commands. (Good dog!) However, while there have been many studies investigating the linguistic abilities of primates, cetaceans, parrots and certain other species, there has been surprising little formal research into the verbal comprehension of dogs. Dogs have been tested for their understanding of specific words and commands, but there has been an absence of research into whether they can understand and distinguish the constituent parts of complex sentences that refer both to objects (e.g., “ball,” “stick” or “newspaper”) and to actions (e.g., “fetch,” “roll over,” or “point”).

In one of these experiments, Pilley and Reid tested whether Chaser could independently understand the meanings of verbs and nouns. In this test, Chaser was asked to respond appropriately when three different commands (take, paw, and nose) were randomly associated with three different stuffed cloth toys (Lips, a toy resembling human lips; ABC, a cloth cube with those letters written on its side; and Lamb, a stuffed lamb) in 14 independent trials using a double-blind procedure. Chaser was familiar with the commands, but none of the three toys had ever been paired with any of the commands prior to the experiment.

The three toys were lined up on a soft pad in front of a one-meter high cloth barrier. During the trials, neither Chaser nor the experimenter could see each other, as the experimenter knelt on one side of the barrier, with Chaser hanging out with the toys on the other side. The experimenter, who had been given a toy and command combination generated with a random number table, gave Chaser his instructions, while a confederate sat to the side where she could see Chaser perform and signal to the experimenter with a hand wave when the trial was over. Here’s a picture of the setup, taken before the experimenter retreated to the other side of the barrier to commence the trial (note that the confederate’s legs are visible to the right of the picture):

The tests were videotaped with sound recording, with three independent raters (not the experimenter or the confederate) scoring whether Chaser chose the correct toy and performed the correct command. Each rater first watched the videotape with the sound turned off (so he/she wouldn’t know which instructions had been given to Chaser), and recorded which command was actually executed towards which toy. After rating all 14 trials, the rater then watched each trial again with the sound turned on in order to assess whether Chaser’s behavior accurately matched the instructions given by the experimenter.

How did Chaser do? Perfectly.

There was absolutely no disagreement among the raters – each judged Chaser to be 100% accurate across the 14 trials, performing the correct command to the correct toy as instructed. As Pilley and Reid put it:

These results clearly support the conclusion that Chaser understood reference – that the verbal noun of an object referred to a particular object with distinct physical features independent of actions directed toward that object.

Comprehending Sentences

Then, earlier this month, Daniel Ramos and Cesar Ades of the University of São Paulo published a study in PLoS One that extended the Chaser research.

In their study, Ramos and Ades tested Sofia, a female mongrel dog, on two-item requests over a two year period, starting when she was a two-month old puppy. The testing consisted of eight progressive phases, during which Sofia first learned some basic vocabulary and then gradually faced increasingly complex tests of her comprehension abilities. The specific phases were as follows:

Learn the names for four objects (ball, key, bottle and stick) and two requests (point or fetch).

When presented with two objects, approach the correct object on request, or perform the correct action upon request.

Perform object and action requests in sequence – that is, first approach the proper object after being given an initial “object request” and then, after being given an “action request,” perform the correct action on the object.

To eliminate the possibility of inadvertent cues from the experimenter, perform the same tests as in phase 4 but with the following control variations: (1) experimenter wearing sun-glasses, (2) experimenter with mouth covered by a cloth band, (3) research assistant absent from the room, (4) unfamiliar person as experimenter, (5) testing in an unfamiliar room, (6) test objects scattered, distant from one another, and (7) new objects of the same category (new balls, keys, etc.) offered.

Perform reversed multi-part requests – that is, in response to compound requests in which the word order has been switched from object-action to action-object (e.g., fetch ball, point ball, fetch key, point key, fetch bottle and point stick), approach the correct object and perform the correct action just as in phase 4.

Perform multi-part requests with new combination object-action pairs (stick fetch and bottle point) that had not been used at all during prior training or tests.

And how did Sofia do? Well, she wasn’t perfect like Chaser, but she was pretty impressive. Her success rate was significantly above chance in all phases except for the final one, in which she had only 3 out of 10 correct responses for both the stick fetch and the bottle point requests. Notwithstanding this one area of underperformance, Ramos and Ades concluded:

Our results suggest that dogs share with “linguistic” animals the capacity to encode in memory at least two heterogeneous items of information to be used in subsequent directed performance, a capacity which, although far from being “an infinite use of finite means” as human grammars are, may have comparative relevance as a forerunner to syntactical functioning.

Now, I know what you are saying. Yes, your dog can do that too. I’m aware that she consistently beats you and your friends at poker, and I’ve seen the video where she plays charades while riding around your house on a Roomba.

You see, that’s actually the issue. Dogs are incredibly good at picking up human signals, which is why carefully-designed experiments are important in ruling out the “Clever Hans” effect (named after a horse who, more than a century ago, amazed crowds with his apparent mathematic abilities, but who was ultimately found to be picking up on involuntary body language cues from his trainer).

By eliminating visual contact between Chaser, Sofia and the experimenters and by adding controls such as having unfamiliar persons issue requests and moving around the objects, the researchers ensured that the dogs had to rely exclusively on words rather than on inadvertent human signals or other contextual clues. By changing the size, shape and color of the requested objects and introducing a new object (the teddy bear), the researchers were able to test whether Sofia was able to generalize and apply concepts to new objects in the same category. By reversing word order and thereby changing the acoustics of compound requests, the researchers were able to rule out the possibility that Sofia was performing based on memorizing the sound properties of requests rather than actually understanding the individual words comprising the requests.

So, you were right all along – your dog really does understand you. The problem is everyone else.

In a previous post, AnimalWise saluted the red-footed tortoise (Geochelone carbonaria) for its Ig Nobel Prize achievements but, in doing so, may have unfairly maligned the tortoise’s cognitive capabilities. To atone for any past disparagement, this post is dedicated to an impressive, and perhaps surprising, red-footed tortoise intellectual accomplishment.

Many social animals are able to solve problems and shortcut the costly process of trial and error learning by simply observing the behavior of their peers. While some have speculated that this type of observational learning is an adaptation for social living that may be unique to animals who live together in groups, a research team led by Anna Wilkinson of the University of Vienna wanted to see whether a decidedly non-social animal, the red-footed tortoise, could also learn by observing others. Wilkinson specifically hoped to test the hypothesis that social learning abilities may simply be a reflection of an animal’s general learning capacity, and that non-social animals may be able to learn by observing peer behavior in fundamentally the same way as they use other environmental stimuli to learn.

Finally – respect for my brains as well as my dashing good looks!

The red-footed tortoises were perfect subjects for this study. The natives of Central and South American forests are naturally solitary, receiving no parental care (once the eggs hatch, it’s every little tortoise for himself and herself!) and, unless presented with a mating opportunity, living apart from other tortoises.

For Wilkinson’s study, eight young (juvenile or sub-adult) tortoises – four randomly assigned to the “non-observer” condition and the other four assigned to the “observer” condition – participated in a series of trials in which they needed to navigate around an obstacle to achieve a food reward. All trials took place in a square arena in which a 40 cm high V-shaped fence separated the tortoise from the desired food:

First, the tortoises in the non-observer groups were each given 12 trials (one per day) in which they were allowed two minutes to solve the task. Between trials, the bark flooring in the arena was redistributed to prevent the tortoises from being able to latch onto any scent trails from prior trials.

Next, the observer group tortoises had their turn. Their trials were identical except that, before each test, they were able to observe a specially-trained tortoise who invariably detoured around the right side of the obstacle and ate the food prize.

The results were unambiguous. While none of the non-observer tortoises ever solved the puzzle (they went up to the fence by the food, but never figured out how to go around the obstacle), all of the observer tortoises succeeded at least twice, with two of them correctly navigating around the barrier on the first attempt.

In other words, the red-footed tortoises have another addition for their trophy room. Not only are they the first red-footed and hard-shelled recipients of the Ig Nobel Prize, they are also the first non-social reptile to display social learning skills, revealing that group living is not necessarily a prerequisite for social learning.

Last week, British parents who had hidden their child’s gender from the world finally revealed that their five year old, now ready to enter school, is a boy. While the parents had hoped to raise their son Sasha in a gender-neutral way (“Stereotypes seem fundamentally stupid. Why would you want to slot people into boxes?”), their approach raised eyebrows and controversy. Were they creating an environment where their child could find his own gender identity, free from crippling societal expectations, or were they conducting a bizarre and possibly harmful experiment on a family member?

Putting aside the issue of whether the parents acted appropriately, the story raises fascinating questions about gender-specific traits and preferences. To what degree are gender differences innate and biological, and to what extent do they arise out of societal modeling and environment?

Some (including Sasha’s parents) may see gender preferences as being primarily influenced by human social pressures, but there are indications of biological influences as well. For example, girls with a particular genetic condition that exposes them to high prenatal levels of androgen often show “masculine” toy preferences, even when their parents strongly encourage them to play with female-typical toys. Given the intertwining impacts of nature and nurture in human societies, can we learn anything from our animal relatives who grow up free from human societal norms?

In this post, I’d like to take a look at two recent studies that examine differing male and female toy preferences in primates.

Male Monkeys Prefer Trucks

First, in 2009 a research team led by Janice Hassett of the Yerkes National Primate Center at Emory University reported on experiments in which they the researchers to see whether rhesus monkeys (Macaca mulatta) would exhibit gender-specific toy preferences similar to those of human children.

In humans, studies have shown that boys gravitate strongly to stereotypically “masculine” toys such as trucks and other vehicles, while girls are less rigid, spending relatively equal amounts of time playing with boy-favored toys and with more traditionally “feminine” toys such as dolls. One hypothesis put forward to explain this difference has been that boys face greater societal discouragement when they play with “girl toys” than girls do in the reverse situation. The researchers figured that by looking at rhesus monkeys, who don’t face comparable social pressures to conform to gender roles, they might be able to illuminate biological influences on toy selection as well.

Of course I'm not playing; you gave me a Raggedy-Ann. Pass me that truck. Now. (photo credit: J.M.Garg, Wikipedia)

In their study, the researchers compared how 34 rhesus monkeys living in a single troop interacted with human toys categorized as either masculine or feminine. The “masculine” set consisted of wheeled toys preferred by human boys (e.g., a wagon, a truck, a car, and a construction vehicle); the “feminine” set was comprised of plush toys comparable to stuffed animals and dolls (e.g., a Raggedy-Ann™ doll, a koala bear hand puppet, an armadillo, a teddy bear, and a turtle). Individual monkeys were released into an outdoor area containing one wheeled toy and one plush toy, with the researchers taping all interactions using separate cameras for each toy, identifying all specific behaviors, and statistically analyzing the results.

The results closely paralleled those found in human children. As with human boys, male rhesus monkeys clearly preferred wheeled toys over plush toys, interacting significantly more frequently and for long durations with the wheeled toys. Also mirroring human behavior, female rhesus monkeys were less specialized, playing with both plush and wheeled toys and not exhibiting significant preferences for one type over the other. Here’s a chart illustrating the similar gender preferences of humans and rhesus monkeys (the information regarding human preferences comes from a 1992 study by Sheri Berenbaum and Melissa Hines):

The researchers noted that these similarities show that distinct male and female toy preferences can arise in the absence of socialization pressures and hypothesized that “there are hormonally organized preferences for specific activities that shape preference for toys that facilitate these activities.”

Barbie Really Is a Stick Figure

Next, in a brief paper published in 2010, Sonya Kahlenberg of Bates College and Richard Wrangham of Harvard University presented the first evidence of wild male and female primates, chimpanzees (Pan troglodytes) in the Kanyawara chimpanzee community of Kibale National Park, Uganda, interacting differently with play objects.

Over a 14 year period, Kahlenberg and Wrangham observed that juvenile Kanyawara chimpanzees tended to carry sticks in a manner suggestive of rudimentary doll play and that the behavior was more common in females than in males. Juvenile chimps, particularly females, would carry around small sticks for hours at time while they engaged in other daily activities such as eating, climbing, sleeping, resting and walking. While the same chimps used sticks as tools for specific purposes, the researchers were unable to discern any practical reason for the stick-carrying. The following chart shows the degree to which female chimps were more likely to engage the in stick carrying behavior:

Age and sex differences in the rate of stick-carrying in chimpanzees. Females: circles, solid line. Males: triangles, dashed line.

The researchers hypothesized that “sex differences in stick-carrying are related to a greater female interest in infant care, with stick-carrying being a form of play-mothering (i.e. carrying sticks like mother chimpanzees carrying infants).” In support of this proposition, they pointed to several factors. First, they never observed stick carrying by any female who had already given birth; that is, stick-carrying ceased with motherhood. Also, the chimps regularly carried sticks into day nests where they “were sometimes seen to play casually with the stick in a manner that evoked maternal play.” Finally, nurturing behavior towards objects like sticks had previously been reported in captive chimps and documented on a couple of occasions in the wild.

Also, the researchers suggested a social rather than biological basis for the behavior. Because regular stick-carrying hasn’t been reported in other wild chimpanzee communities, they proposed that that young Kanyawara chimpanzees may be learning the behavior from each other as a way of practicing for adult roles – a form of social tradition passed between juveniles previously described only in humans. Kahlenberg and Wrangham conclude by noting that:

Our findings suggest that a similar sex difference could have occurred in the human and pre-human lineage at least since our common ancestry with chimpanzees, well before direct socialization became an important influence.

So there you have it. One rhesus monkey study positing a biological and hormonal basis for gender-specific play, and another chimpanzee study emphasizing social learning… At least for now, the threads of nature and nurture impacting gender roles seem difficult to disentangle for non-humans, just as they are for us.

It’s far less common, though, to find relationships where non-humans participate on a more equal footing, where they appear to train us at least as much as we train them. (People who are owned by cats should feel free to rebut this statement in the comment section below.)

Today’s post features one such relationship, the partnership between humans and the greater honeyguide (Indicator indicator), a bird that lives in the trees of sub-Saharan Africa.

Honeyguides and humans have very complementary appetites. Honeyguides get most of their food from beehives, feasting on larvae and wax that they extract from honeycombs (yes, they actually eat and can digest the wax!). Of course humans, too, seek out beehives, although our interest lies more in the bees’ sweet honey, and we’re generally more than happy to leave the wax and grubs for others to enjoy.

The bee-related skills of humans and honeyguides are relatively complementary as well. Honeyguides can fly swiftly across large areas and are expert at locating bee colonies, but have difficulty in extricating the combs on their own. Humans move more slowly along the ground and aren’t so adept at finding colonies, but once we have one in our sights, we’re able to overcome bee defenses and dig the combs out, even when the bees have nested deep within rock crevices and other hard-to-reach locations.

Out of this opportunity for mutualistic benefit, honeyguides and humans have worked out an elaborate interspecies communication system that allows them to work in tandem with certain signals understood by both parties. This partnership has been formally documented in a three year field study conducted in the dry bush country of northern Kenya, focusing on the interactions between honeyguides and the nomadic Boran people who populate the area.

Each partner knows how to get the other’s attention. To attract the birds, the Borans call them with a penetrating whistle (known in the Boran language as Fuulido) that can be heard over a distances of greater than a kilometer and that is made by blowing air into clasped fists, modified snail shells, or hollowed-out palm nuts. Comparably, hungry honeyguides flag down humans by flying up close, moving restlessly from perch to perch, and emitting a double-noted, persistent “tirr-tirr-tirr-tirr” call. (Side note: I’ve been practicing this at home, and it doesn’t seem to attract much other than odd stares and raised eyebrows.)

The joint food expedition commences when the honeyguide flies briefly out of sight and then returns to a nearby, conspicuously visible perch. When the human companion approaches this perch, the honeyguide takes off, displaying its white outer tail feathers, and flies to a new resting place a short distance away, calling loudly when it lands. The Boran partner then approaches the new perch and the bird flies off again, repeating the pattern. As the Borans work with the bird, they whistle and shout to keep the bird interested in guiding. (Again, this doesn’t seem to work too well at home.)

The researchers found that the honeyguides signal the path and distance to the bee colony in a variety of ways. First, they indicate the correct direction through their flight paths, traveling consistently in the direction of the nest and increasing their precision as they near the target. It appears that the know in advance where the nests are located, as the researchers observed the honeyguides briefly visiting nests before dawn, peering into the entrances while it was still dark and the bees were docile.

Also, the honeyguides vary their behavior depending on distance to the hive. For example, when the hive is relatively distant, the birds begin the process with a relatively long disappearance during their first flight; conversely, their first disappearance is briefer when the hive is relatively nearby. Further, the honeyguides stop more frequently and the legs between perches become shorter as they and their human followers approach the nest, especially during the last 200 meters. Finally, the honeyguides select increasingly lower perches as they close in on the colony.

Upon arrival at the destination, the honeyguides perch close to the nest and emits an “indication call.” The researchers describe the scene as follows:

This call differs from the previous guiding call in that it has a softer tone, with longer intervals between successive notes. There is also a diminished response, if any at all, to whistling and shouting by humans. After a few indication calls, the bird remains silent. When approached by the searching gatherer, it flies to another perch close by, sometimes after circling around the nest. The resulting flight path finally reveals the location of the colony to the gatherer. If the honey collector does not (or pretends not to) detect the nest, the bird gives up after a while. It may then leave the area either silently or start a guiding session to another colony. In the latter case, it switches from the indication call to the guiding call and resumes a fairly direct flight pattern. Once the human team members find the nest, it becomes their turn to go to work and hold up their part of the bargain. After using smoky fires to reduce the bees’ aggression, the Boran honey gatherers use tools or their hands to remove the honey comb, and then break off pieces to be shared with their honeyguide partners.

To sum things up, here’s a great BBC video (featuring David Attenborough!) that describes the bird-human partnership and shows the honeyguides in action:

Apparently, parrots aren’t just smart, they’re competitive too. A couple of months ago, we covered recent research findings on contagious yawning in animals, reporting on the rarity of the phenomenon and its potential role as a form of social mimicry or even an indication of empathy. While certain primates clearly do yawn contagiously and dogs may yawn contagiously, the behavior hadn’t been reported in other animals and had been expressly ruled out in red-footed tortoises (although the tortoises may have had the last laugh, as they won the celebrated Ig Nobel Prize for their non-yawns).

Word of our mammal-centric coverage seems to have reached the small, oval ears of the always-influential parrot lobby, though, as just last week the journal Behavioural Processes published a study describing social yawning in budgerigars (Melopsittacus undulatus), the small Australian parrot often referred to as the parakeet. This study provides the first support for contagious yawning in a non-mammal, and even ups the ante by documenting what may be the first instance of contagious stretching, another stereotyped behavior that may play a social role for certain animals. Some may say that the paper’s timing is an utter coincidence and that only someone with delusions of grandeur would believe that it was even remotely linked to the AnimalWise post. We, speaking in our usual royal manner, prefer to think otherwise.

Fascinating, simply fascinating...

Michael Miller, Andrew Gallup and other researchers from the University of the Binghamton conducted an observational study of yawning and stretching in a group of approximately 20 adult male and female budgerigars living together in an aviary as an established flock. Over a period of about a year and a half, the research team video recorded the flock on 23 separate occasions. The recording sessions, each of which lasted 90 minutes, were conducted at varying times of the day, and the researchers took a number of precautions (such as ignoring the first 15 minutes of each tape) to ensure that the flock’s behavior was as natural and undisturbed as possible. Trained reviewers then systematically reviewed all of the tapes, recording the time and occurrence of each yawn and stretch, and categorizing each stretch by whether the bird extended one or both legs.

The researchers’ hypothesis was that, if yawning and stretching were spreading contagiously among the birds, the behaviors would occur in nonrandom “clumps” – that is, rather than being evenly dispersed throughout the recording sessions, multiple yawns (or multiple stretches of the same type) would take place in closely-spaced bouts and then be followed by a long interval until a new priming behavior triggered another bout. Further, they predicted that, although there might be might be overall tendencies tied to particular times of the day (for example, the budgerigars might, on average, yawn more frequently during evening sessions), if the yawning and stretching really were being triggered contagiously, then specific clumping patterns would not repeat themselves when multiple same-time-of-day sessions were compared.

To test their hypotheses, the researchers performed detailed, session-by-session analyses of each type of behavior. For example, they tallied how frequently each behavior occurred, measured the time between adjacent stretches and yawns, and sorted the adjacent pairs into different “bins” depending on the length of the interval. They also analyzed each session for clumping by breaking it down into a large number of short (20 to 30 second) intervals, which allowed them to identify “runs” of consecutive intervals that either did, or did not, contain the behavior in question. Finally, they statistically analyzed their data in a variety of ways to identify patterns and associations.

And the results?

Both yawning and stretching behaviors were indeed clustered within trials, and the period between adjacent yawns and stretches was “strongly biased toward very short (< 20 sec) and very long (> 300 sec) intervals,” especially for the yawns. Also, as hypothesized, despite the clustering for both behaviors, “neither behavior routinely occurred at specific times from the start of a session across multiple recordings at the same time of day. This suggests that the clumping of these behaviors was due to social influences, and not to underlying physiological effects as a result of similar circadian patterns.”

The research team summarized its findings and suggested directions for future investigation as follows:

The observational results presented here suggest that yawning and stretching are at least mildly contagious in budgerigars under semi-natural flock-living conditions. In line with each behavior’s presumed physiological function, contagious yawning and stretching may ultimately coordinate mental state and a group’s collective movements, but future research needs to test these predictions.

So, kudos to the budgerigars! Parrots everywhere can take pride in these findings, which point to previously-unknown areas of avian social signaling and coordination, and which may open up new avenues for studying collective behavior.

wbLast week, I had the pleasure of receiving a note from science writer Mary Bates, informing me she had nominated AnimalWise for a Liebster Blog Award.

“Liebster” is a German word meaning dearest, beloved or favorite, and the Liebster Award is sort of a chain letter among bloggers that’s intended to showcase exceptional up-and-coming blogs (typically, those with 200 or fewer followers). Now, there’s no evaluation committee or formal award process for the Liebster, but in a way it’s even nicer – it’s recognition that a peer has noticed and appreciated your hard work.

I want to thank Mary very much for the recognition. Please check out her blog, which – with good reason – has already received the Liebster Award. Mary writes engagingly about biology, psychology, neuroscience, ecology, and all flavors of animal behavior. She earned her PhD from Brown University, where she researched bat echolocation and bullfrog chorusing (admit it, you’re jealous!). While you’re there, be sure to watch the video she’s posted about Li’l Drac, the adorable baby bat; you’ll be adopting your very own fruit bat before long.

Now, the rules for the Liebster Award are:

Show thanks to the blogger who gave you the award by linking back to them.

Reveal your top five picks and let them know by leaving a comment on their blog.

Post the award on your blog.

Bask in the love from some of the most supportive people on the internet—other writers and artists.

And best of all – have fun and spread the karma.

Without further ado, here are my five nominees:

Endless Forms Most Beautiful: Kimberly Gerson captures and expresses the wonders she sees in the natural world vividly and with grace. Be sure to read about Romeo the wolf and what Kimberly would like you to do if she gets eaten by a polar bear.

Inkfish: Elizabeth Preston, the editor of MUSE, the award-winning children’s science magazine, stretches out her tentacles to bring you entertaining accounts of offbeat and fascinating new research studies relating to biology, psychology, evolution, physics, economics, and everything in between. Inkfish is playful and fun, but always accurate and true to the underlying science.

Puff the Mutant Dragon: Mutant Dragon breathes fire and writes exquisitely. The blog wraps together biology, biochemistry and history and toasts them into a delectable treat. If history was never your thing and you’ve always avoided chemical equations, I especially invite you to dig in – I think you just may find that you’ve found a new favorite cuisine!

Popperfont: David Ng, a molecular geneticist and member of the faculty at the University of British Columbia, has created Popperfont, an eclectic mix of scientific trivia, quotations, graphics, comics, stories and other assorted gems. Stop by Popperfont whenever you’re in the mood for some science fun and fascination.

Empirical Zeal: Aatish Bhatia, a Rutgers University grad student, shares his excitement regarding breakthroughs in diverse areas of science, including evolutionary biology, genetics, neuroscience and physics. Empirical Zeal is what great science blogging is all about: wonderful writing that makes technical topics understandable, accessible and exciting. Visit Empirical Zeal and you’ll see what I mean.

So thanks again to Mary, and I hope you enjoy the five nominee blogs as much as I do!

In the middle of the 1980s, a catastrophic event shattered the lives of a troop of olive baboons (Papio anubis) living in the Masai Mara Reserve in Kenya. While the troop ultimately survived the experience, it emerged as a fundamentally transformed society with new cultural traditions. This is its story.

The troop, known as the Forest Troop, was initially very much like other olive baboon troops – that is to say, an extremely hierarchical and aggressive society, fraught with battles for dominance and bullying of subordinates. While a female will remain with her birth troop for life and automatically inherit her mother’s social ranking, a male reaching adolescence must set off on his own to find a new troop and then jockey with other males for position on the social ladder. The stakes are high, as baboon society is polygamous and dominant males enjoy the best access to mating and food resources.

And so it was. The Forest Troop lived in the woods and slept in trees about a kilometer from the open-air garbage pit of a nearby tourist lodge. Over time, many of its most aggressive males got into the habit of traveling to the garbage pit at dawn in order to scavenge for food, fighting for scraps with the males of a neighboring troop.

Then, in 1983, disaster struck. Spoiled meat that had been discarded in the garbage pit caused a fatal epidemic of bovine tuberculosis. Every single Forest Troop male who had foraged for food at the pit – 46% of the troop’s adult males – died in the outbreak. The remainder of the devastated troop, comprised solely of females and less aggressive males, survived.

In the wake of the outbreak, researchers who had been observing the Forest Troop noticed a dramatic reduction in certain types of aggressive behavior within the troop, not a particularly surprising observation given the loss of all of the most aggressive males in the troop. However, because the researchers wanted to focus on an intact troop that hadn’t experienced social disruption, they turned their attention away from the Forest Troop and shifted their efforts to studying a nearby troop that hadn’t been impacted by the outbreak.

A number of years later, though, the researchers returned to the Forest Troop and noticed something fascinating – even though there had been a complete changeover in the troop’s adult males, the troop’s less aggressive behavioral features had persisted. That is, a new generation of baboons in the Forest Troop appeared to be carrying on what amounted to a cultural tradition of lessened baboon aggression.

Geez, another housewarming party?! That Forest Troop has GOT to be some sort of a cult or something. (photo: Philippe_Boissel)

In order to analyze the changed behavior more rigorously, the researchers engaged in what’s known as a “focal sampling” process. They systematically recorded the social behavior of individual Forest Troop baboons from 1993 through 1996, and then compared those observations to two other data sets that served as controls – pre-outbreak observations they had made of the Forest Troop from 1979 to 1982, and mid-1990s observations of a different olive baboon troop.

What they found bore out their initial impressions. In particular, the new generation of Forest Troop baboons displayed patterns of dominance and aggression behavior that created less stress for low-ranking males. While the overall number of incidents involving aggression and dominance behavior was comparable to that seen in the control cases, the mix was different. Forest Troop confrontations were now significantly more likely to involve closely-ranked males, as opposed to the control group behavior pattern in which very high ranking males tended to pick on the lowest-ranking ones. This is notable, as confrontations between baboons with large power disparities typically reflect harassment rather than true competition and can be particularly stressful to the lower-ranking subordinates. Moreover, in the post-epidemic Forest Troop, males acted less aggressively towards females, engaged in more social grooming with females, sat in closer proximity to other baboons, and were more likely to have adult females, infants, adolescents, and juveniles as neighbors. Finally, the researchers found that subordinate baboons in the kinder and gentler Forest Troop had much lower levels of glucocorticoids, adrenal hormones secreted in response to stress, than did subordinates in the control groups.

C’mon, Dad, faster! Bumbo and Uncle Phil are waaaay ahead of us!

The researchers next considered how the peaceful new social traditions of the Forest Troop were being passed on to new males joining the troop: were troop members teaching the newcomers to be less aggressive, were new arrivals learning through observation or because they had more opportunities for friendly interactions, or was self-selection causing less aggressive males to gravitate toward this more peaceful troop? The researchers found that new males acted with typical aggression upon arriving at Forest Troop and were greeted with the usual belligerence from other males, but that the Forest Troop females were now uncharacteristically welcoming to the new arrivals, grooming them and otherwise treating them as established residents. Because the females didn’t seem to be engaged in active teaching behavior (they showed the same friendly behavior to even the most aggressive of the newcomers), the researchers concluded that the peaceful Forest Troop cultural traditions were most likely being passed on as newcomers observed more positive interactions with females and had more opportunities to relate non-aggressively themselves.

So, out of ashes of death, a baboon troop forged a new culture and found a way to maintain its peaceful traditions, passing them along to new generations. Makes one think….

If you’re a female elephant, there’s a right way and a wrong way to play the mating game. To maximize your chances of reproductive success, it’s best to pair up with a dominant bull elephant in musth, a state of heightened arousal in which testosterone courses through the bull’s body, increasing both his sex drive and his aggression. A high-ranking musth elephant not only makes the fittest mate, but he can protect you by scaring off the less desirable younger males who would otherwise chase you around.

An experienced female knows this well, and plays the game accordingly. When she goes into heat – or oestrus – and attracts male suitors through chemicals in her urine, she gives impressive senior bulls the green light by holding her tail high, walking with an exaggerated gait, and exchanging affectionate trunk caresses. Lower-ranking young males don’t fare so well. She actively avoids them and, to the extent they aren’t chased off by her favored partner, she’ll often spurn their advances by running away. (Little known fact: female African elephants can typically outrun male ones.)

It’s not so easy for a young female entering oestrus for the first time. She sometimes runs from the larger musth males, who can weigh more than twice as much as her, and not infrequently ends up consorting with a series of younger, lesser males. This can lead to unfortunate results, especially when you consider that an elephant pregnancy lasts 22 months.

Now, though, there’s evidence that experienced females may help their younger relatives in sorting through the confusing tangle of elephant sexual dynamics. These helpful older elephants – sisters, aunts, mothers, and matriarchs – appear to simulate oestrus in order to show their innocent family members how to act, enabling them to avoid the pitfalls of poor mating choices.

If I said you had a beautiful trunk, would you hold it against me? (photo: WildlifeDirect, Dzanga Forest Elephants)

After hearing anecdotal accounts of this behavior, a team led by Lucy Bates of the University of St. Andrews decided to dig deeper by taking advantage of an invaluable resource – a comprehensive multi-decade database cataloging the daily life activities of 2,200 Amboseli elephants compiled by Cynthia Moss, Joyce Poole, and other researchers as part of the Amboseli Elephant Research Project (AERP).

Bates and her colleagues systematically combed through 28 years of detailed AERP records and located all occasions on which an observer had concluded that an identifiable elephant was in oestrus (based on postural and behavioral changes in females, interactions with males, etc.). In total, they found descriptions of 999 oestrus events, slightly less than 10% of which (98 events) recorded two or more members of the same elephant family displaying simultaneous oestrus behavior.

Next, the researchers cross-referenced these accounts with AERP demographic records to find any that must have been “false” oestrus events, which they defined as oestrus-like behavior by a female who was either already pregnant, in a state of lactation-induced infertility, or senescent (which they deemed to be the case if she was over 50 years old, had not given birth to any calves during the prior five years, and had no subsequent calves).

They discovered that, while false oestrus behavior was relatively rare (occurring only 19 times and representing only about 2% of all recorded oestrus events), its timing was fascinating. Very often, it occurred just when a young relative was coming into oestrus for the first time.

Even though simultaneous oestrus behavior had been recorded less than 10% of the time, over half of the false oestrus events (10/19) clearly occurred at the same time as the true oestrus of a young female family member who had never given birth. Further, subsequent birth records confirmed that on four additional occasions a false oestrus event occurred during the month that a young relative conceived her first calf (that is, the young female must have been in oestrus at the time, even though it wasn’t specifically called out in the AERP database). Finally, one of the false oestrus events occurred simultaneously with the genuine oestrus of a female relative who had given birth before. Thus, the large majority of the false oestrus events – 15 of 19 – coincided with true oestrus events, in most cases, the first oestrus of a young relative. (Moreover, note that the balance of the false oestrus events could also have coincided with true ones if, as in the four cases described above, the true oestrus event simply had not been observed or recorded in the AERP database.)

The researchers then examined various hypotheses that might explain the false oestrus behavior:

That false oestrus merely results from hormonal changes and has no functional purpose;

That it somehow induces sexual receptivity in the simulating female, thereby increasing her own chances of successfully reproducing;

That it indirectly benefits the simulating female by providing a young family member with increased access to suitable males (this type of indirect benefit is known as an inclusive fitness benefit); or

That it indirectly benefits the simulating female by encouraging a confused younger relative to engage in more suitable oestrus behavior (another potential example of inclusive fitness).

They quickly rejected the all but the final hypothesis. For one, hormonal changes couldn’t adequately explain either the observed patterns (false oestrus occurred in both pregnant and non-pregnant females, as well as during all stages of pregnancy) or the higher-than-expected coincidence of false oestrus with the genuine oestrus events of inexperienced relatives. Second, it was clear that the simulating elephants weren’t improving their own reproductive success: in 14 of 19 cases the simulating the female was already pregnant, and in four others she was senescent. Third, AERP records revealed that false oestrus behavior had no impact on the number of available males, the relative percentage of males who were in musth, or the amount of sexual activity engaged in by inexperienced female.

Ultimately, the researchers concluded that:

Further data is required to confirm or reject the hypothesis that this behaviour functions to teach the young, naïve females, but we suggest that it remains the only viable possibility based on the current analyses.

In particular, they noted that additional research and data collection was necessary to explain the instances in which false oestrus didn’t appear to coincide with an inexperienced relative’s oestrus as well as to support the notion that inexperienced females were able to correct substandard mating behavior after they were shown what to do by their older relatives.

In the meantime, though, you’d be well advised to stay away from those frivolous young guys and find yourself a dashing older bull who knows his way around the herd.

I’ve always found friendly interactions between animals of different species to be oddly reassuring. After all, the world can’t be all that bad a place if two animals, separated by differing genetic backgrounds and behavioral imperatives, can find a way to reach across the biological divide and share something, something joyful and positive.

Because of this, I’m an absolute sucker for all of those YouTube videos of cats curling up with mice, horses who befriend sheep, elephants and dogs who are inseparable, and the like. You know the ones I mean.

Many times, though, these are artificial pairings that spring up after we humans have altered the environment, habituating or even confining the animals with one another. While these human-influenced relationships can be incredibly heartwarming, it somehow seems even more magical when animals forge connections across species boundaries in the wild, in their native habitats and without any human intervention.

With that background, I’d like to introduce a paper published last year in the journal Aquatic Mammals1, which reports on two separate playful and – as you’ll see – uplifting encounters between bottlenose dolphins (Tursiops truncatus) and humpback whales (Megaptera novaeangliae).

The first took place on a January afternoon off the northwest coast of Kauai, when a group of eight bottlenose dolphins met up with a pair of humpback whales. Two of the dolphins – apparently adults – approached one of the whales, first appearing to surf the pressure wave created by the whale’s head as it swam, and later taking turns lying perpendicularly across the whale’s rostrum when it surfaced to breathe. Then, while one of the dolphins lay balanced over the end of its rostrum, the whale stopped and slowly lifted the dolphin high into the air. The dolphin maintained an arched position and made no effort to escape, allowing the whale to continue lifting until it was nearly vertical in the water, at which point the dolphin slid down the whale’s rostrum, dove into the water, and porpoised back to its fellow dolphins.

Here’s a color photo of the dolphin just about to go whale-sliding:

Look Ma, No Hands! (photo credit: L. Mazzuca)

And here’s a black and white series of shots that captures the full adventure sequence:

The second encounter also occurred on a January afternoon, this time off the northwest coast of Maui, when an adult female bottlenose dolphin swam up to a mother humpback whale and her calf. After diving underwater, the dolphin and mother whale resurfaced with the dolphin resting across the mother whale’s rostrum. The mother then proceeded to lift the dolphin a total of six times over 8.5 minutes, with the dolphin either lying on her stomach or right side during the lifts, which varied in length from four to 45 seconds. Again, the dolphin made no attempt to escape and held her position in such a way as to facilitate the whale’s lifting.

Here’s a sequence of photos showing this second duo demonstrating the proper technique for lifting a relaxed-looking dolphin:

The authors of the Aquatic Mammals paper considered alternate explanations for these interactions, including whether they represented an aggressive whale response to an antagonistic dolphin approach, whether the whales were demonstrating concern regarding perceived distress in the dolphins, or whether the cetaceans were simply playing together. They found the first two hypotheses to be unlikely – among other things, the interactions were too cooperative and relaxed in pace to be aggressive, and the dolphins were in good health and showed no evidence of distress. In the end, while the authors didn’t rule out the possibility that maternal instinct was involved in the whales’ lifting behavior, they concluded that the best explanation was that these were simply instances of interspecies play between the bottlenose dolphins and humpback whales.

Further, these bouts of play between dolphins and whales may not be all that uncommon, as back within the friendly confines of YouTube I was able to locate a video documenting another episode in which a bottlenose dolphin went for a ride on the rostrum of a humpback whale:

…

Play may serve a number of important purposes – for example, it may provide an avenue for intelligent, social animals like dolphins and whales to experiment with their surroundings, hone their physical skills and learn how to interact collaboratively with others. But aside from any practical evolutionary significance, I like to think of these encounters as illustrating how animals can, on occasion, take a few minutes away from the serious business of survival to share some pure joy and wonder with a fellow being, even a fellow being of a different species.

So, all of this is comforting. If dolphins and whales (and other animals who form interspecies bonds) can find a way to communicate playfulness with each other and to share experiences without any kind of a common language, perhaps we humans can do a bit better ourselves. Maybe some of the divides we see today – political discord, religious conflict, international posturing, cultural and racial inequities – aren’t so unbridgeable after all. Perhaps all we need to do is to remember an uplifting dolphin story or two.

The name tags kept disappearing, and the staff at Melbourne’s Dingo Discovery and Research Centre was mystified. After romping around the grounds of the dingo sanctuary, Sterling, an 18 month old sub adult male, and his two canine companions spent time in an indoor enclosure that had a name tag posted on the outside of the steel mesh wall. The tag was positioned 1.7 meters above the ground, well out of dingo-reach. Still, it kept vanishing.

As reported in a paper published online last week in Behavioural Processes,1 the caretakers decided that it was time solve the mystery. First, they hung a small plastic envelope filled with food near the name tag and watched to see what the dingoes would do. The dingoes were having none of that, however – as long as observers were around, the dingoes studiously ignored both the name tag and the envelope of food. Since the direct approach clearly wouldn’t work, the staff resorted to sneakiness, rigging up a video camera and then leaving the dingoes to their own devices.

Success! When the staff returned to the enclosure, they found that the food was gone and, more importantly, that the videotape reflected perhaps the first documented instance of tool use by a member of the Canid family. As described in the Behavioural Processes paper:

Big deal, Lassie; when Timmy fell down *my* well, I hoisted him out using a system of pulleys. (Sterling at Dingo Discovery and Research Centre, photo by Dingo Lyn)

[A]fter several unsuccessful attempts at jumping for the envelope, Sterling “solved” the task by first moving and then jumping up onto a trestle table (1.2 m × 0.6 m × 0.73 m) which allowed him to gain the additional height necessary to reach the food item. To move the table, Sterlingclamped his mouth onto the strut between the legs of the table. He then walked backwards, dragging the table approximately 2 m, until it appeared that either his back leg or tail touched the enclosure mesh. He then jumped onto the table, but as he was still at least a body-length away from the envelope, he had to span the gap between the table and the enclosure mesh by propping his front paws onto the mesh gradually moving them towards the envelope. At full stretch, he reached the envelope on his second attempt.

While this account of Sterling’s actions may sound impressive, it’s even more striking when seen on video:

…

Bradley Smith of the University of South Australia and his colleagues noted in their paper that Sterling’s behavior appeared to be spontaneous – he had never been trained or encouraged to position the table in order to reach food (or name tags) – but they cautioned that they had to rely on information provided by the sanctuary’s staff regarding Sterling’s (lack of) relevant training in the past.

No problem, just bring me a socket wrench, a crow bar and three sticks of gum... (Sterling at Dingo Discovery and Research Centre, photo by Dingo Lyn)

Sterling, for his part, was no one-hit wonder. According to sanctuary staff, from an early age Sterling was adept at manipulating his environment to serve his purposes. For example, during one breeding season he used his front paws to roll a barrel to a wall, jumped up on the barrel, scrambled over the wall, and approached a female dingo in another area of the sanctuary. Also, the staff and research team later videotaped separate occasions in which Sterling used his mouth to drag a plastic dog kennel to differing locations around his enclosure, allowing him to stand on the kennel and peer over walls into neighboring dingo enclosures.

Thus, while the researchers couldn’t exclude the possibility that Sterling’s problem-solving abilities were the result of observational learning or that they had somehow been reinforced when he was younger, they rightly recognized that he appeared to be engaging in “high order behaviour” in using tools within his environment to solve complex problems. (Indeed, on the face of it, Sterling’s problem-solving is quite very reminiscent of Kandula the elephant’s insightful use of a box within his yard to solve an out-of-reach food challenge.)

So, now that you know what canines are capable of, please feel free to ask your dog Barkley when he’s going to get around to assembling that futon you bought at Ikea. No more excuses.

2As we’ve noted in previous posts (see, for example, the post on the poison rat and the tuskfish tool post), scientific authorities have defined the concept of “tool use” in various ways. In the Beck and Shumaker treatise discussed in the poison rat post, the authors describe a couple of anecdotal instances that may qualify as canid tool use under their broad definition, including an account of a wolf mother who used meat as a “baiting” and “enticing” tool to distract her young pup. Fox, M. (1971). Possible Examples of High-Order Behavior in Wolves Journal of Mammalogy, 52 (3) DOI: 10.2307/1378613.